Preparation of magnesium alkylphenates and their use as detergent-dispersant additives for lubricating oils

A method of preparing magnesium alkyl phenates comprising:

• (A) preparing a suspension of active magnesium oxide in methanol, said suspension containing up to about 10 percent by weight of active magnesium oxide, referred to the weight of the methanol;
• (B) contacting at a temperature between about 0.degree. and 40.degree. C. said suspension with a mixture consisting essentially of:
• (a) an alkyl phenol having at least one C.sub.6 -C.sub.60 alkyl substituent,
• (b) a dilution oil, and
• (c) a heavy alcohol of a boiling point of between about 100.degree. and 200.degree. C. that is not a diol,
• the ratio of the number of mols of active magnesium oxide to the number of recurrent phenolic OH units being between about 0.25 and 2, the amount of dilution oil being between about 0 and 140 percent by weight, referred to the weight of alkyl phenol, and the molar ratio of heavy alcohol to active magnesium oxide being between about 0 and 4, the said molar ratio being at least 1.2 when the ratio of the number of active magnesium oxide mols to the number of recurrent phenolic OH units is greater than about 0.75;
• (C) and carbonating the resultant medium under pressure with carbon dioxide at a temperature between about 0.degree. and 40.degree. C.